Guys, I asked Patrick at Pro Systems about my carb issue and he sent some really detailed information. Not sure if any of you have his product, but wanted to pass it along. One thing that strikes me is that he's saying a typical idle RPM is about 1,100 to 1,200? That sounds high, but. . . right now I'm idling at about 850 to 900. Anyway. . . .
Hi John,
It may be rich at an idle and putting fuel in the pipes that has to dissipate.
Here is about everything you'll ever need to know about tuning that carb for most applications and weather conditions.
Read and UNDERSTAND all of this..its great info.
1. Be sure the float levels are no more than 25-40 percent up into the glass (at 50 percent up it will pour raw fuel into the engine).
2. Set the four small Idle mixture screws in the 1.5-2.5 full turn range is typical.
3. BE SURE the throttle shafts are open a similar amount.
Next, turn the idle mixture screws in evenly until it hesitates when you snap the throttle.
Then turn them back out until the hesitation goes away.
If you are at 1.5 turns or less on the mixture screws at this point, then we need to REMOVE the rear metering block and
use an allen wrench and unscrew/remove the two brass restrictors from PORT 2 in the REAR of the main body (see photo).
Then readjust the idle mixture screws again.
Also be sure you are not idling at too low of an RPM as that will cause excessive reversion in the intake manifold and load the cylinders with exhaust. Typically a neutral rpm of 1100-1200 rpm.
If you have already removed the rear restrictors from the main body, NEXT drill the idle air bleeds out (located in the outer four corners) .010 larger at a time until the mixture screws are required to be at 2 turns out as a baseline. Any further in and it will stall or hesitate at the snap of the throttle.
As you drill them out you will be required to turn the idle mixture screws out to regain good idle control.
If after doing these changes it is still rich, possibly it needs a hotter sparkplug or more base ignition timing (typically a MINIMUM of 22 degrees of timing at an idle for most decent sized camshafts).
You'll know you got it right, as when you pull it into gear or put a mild load on it to move it will not drop excessively or require a lot of throttle to move.
If it drops excessively or requires a lot of throttle it is too lean, if it requires you to roll and roll it over to clean the plug up to restart it is too rich.
Thanks
Patrick James
727-490-5717
Hi John,
It may be rich at an idle and putting fuel in the pipes that has to dissipate.
Here is about everything you'll ever need to know about tuning that carb for most applications and weather conditions.
Read and UNDERSTAND all of this..its great info.
1. Be sure the float levels are no more than 25-40 percent up into the glass (at 50 percent up it will pour raw fuel into the engine).
2. Set the four small Idle mixture screws in the 1.5-2.5 full turn range is typical.
3. BE SURE the throttle shafts are open a similar amount.
Next, turn the idle mixture screws in evenly until it hesitates when you snap the throttle.
Then turn them back out until the hesitation goes away.
If you are at 1.5 turns or less on the mixture screws at this point, then we need to REMOVE the rear metering block and
use an allen wrench and unscrew/remove the two brass restrictors from PORT 2 in the REAR of the main body (see photo).
Then readjust the idle mixture screws again.
Also be sure you are not idling at too low of an RPM as that will cause excessive reversion in the intake manifold and load the cylinders with exhaust. Typically a neutral rpm of 1100-1200 rpm.
If you have already removed the rear restrictors from the main body, NEXT drill the idle air bleeds out (located in the outer four corners) .010 larger at a time until the mixture screws are required to be at 2 turns out as a baseline. Any further in and it will stall or hesitate at the snap of the throttle.
As you drill them out you will be required to turn the idle mixture screws out to regain good idle control.
If after doing these changes it is still rich, possibly it needs a hotter sparkplug or more base ignition timing (typically a MINIMUM of 22 degrees of timing at an idle for most decent sized camshafts).
You'll know you got it right, as when you pull it into gear or put a mild load on it to move it will not drop excessively or require a lot of throttle to move.
If it drops excessively or requires a lot of throttle it is too lean, if it requires you to roll and roll it over to clean the plug up to restart it is too rich.
Thanks
Patrick James
727-490-5717
